A novel biomass pyrogenic index and its application coupled with black carbon for improving polycyclic aromatic hydrocarbon source identification.

To accurately subdivide the sources of polycyclic aromatic hydrocarbons (PAHs), the composition characteristics of 36 total polycyclic hydrocarbons (T-PAHs; 16 parent PAHs and 20 alkylated PAHs [A-PAHs]) in biomass-residue samples were analyzed. A novel biomass pyrogenic index (BPI) was defined based on A-PAH-fingerprinting differences between biomass-combustion and petroleum sources of PAHs and the sum of the concentrations of pyrene, fluoranthene, benzo[a]anthracene, and alkylated homologs) divided by the ∑value of EPA PAHs with 2-3 rings. BPIs of < 0.5 and > 0.5 indicated that the PAHs originated mainly from biomass combustion and petroleum, respectively. And the ∑targeted A-PAH pairs influencing the BPI/black carbon (BC) ratio was used to identify PAH sources in surface-sediment samples, using 0.5 as the threshold to distinguish between different sources across the strait. The columnar sediments were used to verify the accuracy of two source-identification methods. The results revealed that the main PAH sources changed since 2005, which is highly consistent with those obtained using positive matrix factors and a changing trend in the main types of local energy use. These results highlight the significance of A-PAHs in accurately identifying PAH sources and suggest that applying compositional differences in BC from different sources for PAH-source identification merits further study.

Interactions between hydroxylated polycyclic aromatic hydrocarbons and serum albumins: multispectral and molecular docking analyses.

Hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) can bind to serum albumin and influence their distribution and elimination in organisms. Here, multispectral analysis and molecular docking methods were used to investigate the binding mechanism of two OH-PAHs, 1-hydroxyphenanthrene (1-OHPhe) and 9-hydroxyphenanthrene (9-OHPhe), with two homologous serum albumins, human serum albumin (HSA) and bovine serum albumin (BSA). The quenching constants of HSA with 1-OHPhe and 9-OHPhe were much larger than those for BSA. Energy transfer from the tryptophan (Trp) residues in HSA to 1-OHPhe and 9-OHPhe was more probable than from Trp in BSA. The interactions of 1-OHPhe and 9-OHPhe with Trp in HSA and BSA altered the microenvironment of Trp. Molecular docking results revealed that the binding modes and binding forces of 1-OHPhe and 9-OHPhe with HSA and BSA were different. The two OH-PAHs were used as fluorescent probes to analyze the microenvironmental hydrophobicities of HSA and BSA, which were distinctly different. The structural difference between HSA and BSA induced significant variations in their binding behaviour with 1-OHPhe and 9-OHPhe. Moreover, HSA was more susceptible to 1-OHPhe and 9-OHPhe than BSA. This work suggests that the differences between the two serum albumins should be considered in related studies.

Metformin attenuates atherosclerosis and plaque vulnerability by upregulating KLF2-mediated autophagy in apoE-/- mice.

Atherosclerosis is a chronic lipid disfunction and inflammatory disease, which is characterized with enriched foam cells and necrotic core underneath the vascular endothelium. Therefore, the inhibition of foam cell formation is a critical step for atherosclerosis treatment. Metformin, a first-line treatment for Type 2 diabetes, is reported to be beneficial to cardiovascular disease. However, the mechanism underlying the antiatherogenic effect of metformin remains unclear. Macrophage autophagy is reported to be a highly anti-atherogenic process that promotes the catabolism of cytosolic lipid to maintain cellular lipid homeostasis. Notably, dysfunctional autophagy in macrophages plays a detrimental role during atherogenesis. Krueppel-like factor 2 (KLF2) is an important transcription factor that functions as a key regulator of the autophagy-lysosome pathway. While the role of KLF2 in foam cell formation during the atherogenesis remains elusive. In this study, we first investigated whether metformin could protect against atherogenesis via enhancing autophagy in high fat diet (HFD)-induced apoE-/- mice. Subsequently, we further determined the molecular mechanism that whether metformin could inhibit foam cell formation by activating KLF2-mediated autophagy. We show that metformin protected against HFD-induced atherosclerosis and enhanced plaque stability in apoE-/- mice. Metformin inhibits foam cell formation and cellular apoptosis partially through enhancing autophagy. Mechanistically, metformin promotes autophagy via modulating KLF2 expression. Taken together, our study demonstrates a novel antiatherogenic mechanism of metformin by upregulating KLF2-mediated autophagy.

Effects of multiwalled carbon nanotubes on the dissolved organic matter released by Prorocentrum donghaiense: Results of spectroscopic studies.

Many reports have investigated the effects of carbon nanotubes (CNTs) on the properties of terrestrial dissolved organic matter (DOM), which could significantly altered its binding affinity for contaminants. However, the effects of CNTs on algogenic DOM are largely unknown. To address this issue, the properties of algogenic DOM released by Prorocentrum donghaiense (P. donghaiense-DOM) under the stress from 0.1 to 10.0 mg/L graphitized multiwalled CNTs were nondestructively characterized by the use of UV-visible absorption and fluorescence excitation-emission matrices with parallel factor analysis. The results showed that the changes in the properties of P. donghaiense-DOM were highly dependent on the CNTs concentration. The properties of P. donghaiense-DOM under 0.1 mg/L CNTs treatment showed no obvious differences compared to the control. The addition of 0.5-10.0 mg/L CNTs changed the release pathways of P. donghaiense-DOM, resulting in significant alterations to the properties of P. donghaiense-DOM. The aromaticity, molecular weight, protein-like and humic-like components were enhanced under stress from 0.5 to 1.0 mg/L CNTs on day 4, which can be ascribed to the overproduction of extracellular DOM (EDOM) that occurred in response to the significant increase in intracellular ROS levels. CNTs at 5.0 and 10.0 mg/L significantly induced membrane damage to P. donghaiense on day 4, which led to the leakage of intracellular DOM (IDOM) and then increased the molecular weight and protein-like components but decreased the aromaticity and humic-like components. After the P. donghaiense recovered to its normal growth under 0.5-10.0 mg/L CNTs treatments, the changes in the properties of P. donghaiense-DOM were attributed to the release pathways of P. donghaiense-DOM that were governed by the production of EDOM and the leakage of IDOM in the stationary and declining phases, respectively.

Neurodevelopmental toxicity assessments of alkyl phenanthrene and Dechlorane Plus co-exposure in zebrafish.

Alkyl phenanthrene (A-Phen) and Dechlorane Plus (DP) are ubiquitous environmental pollutants that widely co-exist in the environment. It has been established that both A-Phen and DP elicit neurotoxicity, but the potential interactive toxicity of these contaminants is not well-known. To determine whether a mixture of A-Phen and DP would exhibit interactive effects on neurodevelopment, we co-exposed 3-methylphenanthrene (3-MP), a representative of A-Phen, with DP. Our results illustrated that exposure to 5 or 20 µg/L 3-MP alone or in combination with 60 µg/L DP caused neurobehavioral anomalies in zebrafish. In accordance with the behavioral deficits, 3-MP alone or co-exposed with DP significantly decreased axonal growth of secondary motoneurons, altered intracellular Ca2+ homeostasis and induced cell apoptosis in the muscle of zebrafish. Additionally, 3-MP alone or co-exposed with DP significantly increased reactive oxygen species (ROS) and the mRNA levels of apoptosis-related genes. These findings indicate that 3-MP alone or co-exposed with DP induces neurobehavioral deficits through the combined effects on neuronal connectivity and muscle function. Chemical analysis revealed significant increases in 3-MP and DP bioaccumulation in zebrafish co-exposed with 3-MP and DP. Elevated bioaccumulation resulting from mixture exposure may represent a significant contribution of the synergistic effects observed in combined chemical exposure.

Insight into the heterogeneous adsorption of humic acid fluorescent components on multi-walled carbon nanotubes by excitation-emission matrix and parallel factor analysis.

The heterogeneous adsorption behavior of commercial humic acid (HA) on pristine and functionalized multi-walled carbon nanotubes (MWCNTs) was investigated by fluorescence excitation-emission matrix and parallel factor (EEM- PARAFAC) analysis. The kinetics, isotherms, thermodynamics and mechanisms of adsorption of HA fluorescent components onto MWCNTs were the focus of the present study. Three humic-like fluorescent components were distinguished, including one carboxylic-like fluorophore C1 (λex/λem= (250, 310) nm/428nm), and two phenolic-like fluorophores, C2 (λex/λem= (300, 460) nm/552nm) and C3 (λex/λem= (270, 375) nm/520nm). The Lagergren pseudo-second-order model can be used to describe the adsorption kinetics of the HA fluorescent components. In addition, both the Freundlich and Langmuir models can be suitably employed to describe the adsorption of the HA fluorescent components onto MWCNTs with significantly high correlation coefficients (R2> 0.94, P< 0.05). The dissimilarity in the adsorption affinity (Kd) and nonlinear adsorption degree from the HA fluorescent components to MWCNTs was clearly observed. The adsorption mechanism suggested that the π-π electron donor-acceptor (EDA) interaction played an important role in the interaction between HA fluorescent components and the three MWCNTs. Furthermore, the values of the thermodynamic parameters, including the Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°), showed that the adsorption of the HA fluorescent components on MWCNTs was spontaneous and exothermic.

Effects of flooding and aging on phytoremediation of typical polycyclic aromatic hydrocarbons in mangrove sediments by Kandelia obovata seedlings.

A laboratory experiment was conducted to evaluate the effects of flooding and aging on the phytoremediation of naphthalene (Nap), anthracene (Ant) and benzo[a]pyrene (B[a]P) in mangrove sediment by Kandelia obovata (K. obovata) Druce seedlings. Flooding increased dissipation efficiency in the rhizosphere zone from 69.47% to 82.45%, 64.27% to 80.41%, and 61.55% to 78.31% for Nap, Ant and B[a]P, respectively. Aging decreased dissipation efficiency significantly. Further investigation demonstrated that increased enzyme activity was one of important factors for increasing PAHs dissipation rates in flooded mangrove sediments. Moreover, a novel method for in situ quantitative investigation of PAHs distribution in root tissues was established using microscopic fluorescence spectra analysis. Subsequently, the effects of flooding and aging on the distribution of PAHs in root tissues were evaluated using this established method. The order of bioavailable fractions of PAHs after phytoremediation was as follows: non-aging/non-flooding>flooding>aging.

In Situ Investigating of the Interaction of Phenanthrene and Alkyl Phenanthrene with Humic Acid with Laser Induced Nanoseconds Time Resolved Fluorescence Quenching Method.

Investigations both on the binding properties and mechanisms of parent polycyclic aromatic hydrocarbons (PAHs) and alkyl PAHs with humic acid (HA) are crucial to understand the environment behavior and bioavailability of PAHs in aquatic ecosystems. Thus, a novel approach for in situ investigation of the interactions between parent PAHs and alkyl PAHs, exemplified by Phenanthrene (Phe), 9-Ethylphenanthrene (9-EP) and Retene (Ret), and HA was established by using fluorescence quenching method with laser-induced nanosecond time-resolved fluorescence (LITRF). By changing the delay time of 50 ns, the fluorescent interference of HA can be eliminated effectively and the concentrations of free Phe, 9-EP and Ret can be determined directly. The binding characteristics of the dissolved HA and Phe, 9-EP and Ret were described by Freundlich nonlinear isothermal model. The results of the model parameters and the single point binding coefficients KOC of Phe, 9-EP and Ret with HA by LITRF quenching method were consistent with those of the conventional fluorescence quenching method. Nonlinear bindings of Phe, 9-EP and Ret to HA were also observed because of the parameter n values below 1, and the degree of nonlinearity of Phe was lower than 9-EP and Ret duo to the n value of Phe larger than 9-EP and Ret. At a same given equilibrium concentration, the KOC of Phe was lower than 9-EP and Ret, and that of 9-EP was near to Ret. The binding affinity of the three PAHs increased with decreasing the equilibrium concentration. The binding characteristics of PAHs with HA largely depends on their hydrophobicity, substituent groups and its ability to fit into hydrophobic cavities in HA. The fluorescence lifetimes of Phe, 9-EP and Ret in presence of HA were 36.90, 35.34 and 35.13 ns, meanwhile the fluorescence lifetimes of Phe, 9-EP and Ret in absence of HA were 36.36, 35.34 and 35.84 ns. There was no significant difference of three PAHs fluorescence lifetime with or without HA, indicating the quenching mechanism for Phe, 9-EP and Ret with HA were primarily static quenching. The LITRF quenching method could be used to in situ explore the interactions between PAHs and HA, which could be contribute to realize the PAHs risk assessment in real time.

Combining a tunable pinhole with synchronous fluorescence spectrometry for visualization and quantification of benzo[a]pyrene at the root epidermis microstructure of Kandelia obovata.

The adsorption of polycyclic aromatic hydrocarbons (PAHs) by mangrove roots and their transport to chloroplasts is a potentially critical process that reduces the carbon sequestration efficiency of mangroves. Yet the crucial initial step, the distribution and retention of PAHs at the root epidermis microstructure, remains unclear. A novel method with a spatial resolution of 311 nm was developed for visualizing and quantifying benzo[a]pyrene (B[a]P) at the root epidermis microstructure (0.096 mm2) of Kandelia obovata (Ko). This method combined a tunable pinhole in laser confocal scanning microscopy with synchronous fluorescence spectrometry to reduce the auto-fluorescence interference in locating B[a]P and improve quantitative sensitivity. The linear range for the established method was 0.44-50.00 ng mm-2, with a detection limit of 0.063 ng mm-2 and a relative standard deviation of 9.45%. In a 60-day hydroponic experiment, B[a]P was primarily adsorbed along the epidermis cell walls of secondary lateral roots and lateral roots, with retained amounts of 0.65 ng mm-2 and 0.49 ng mm-2, respectively. It was found to cluster and predominantly accumulate at the epidermal cell surfaces of taproots (0.24 ng mm-2). B[a]P might enter inner root tissues through the root epidermal cell walls and surfaces of Ko, with the cell walls potentially being the main route. This study potentially provides a pathway for visualizing and quantifying B[a]P entering inner root tissues of mangroves.

Effects of polystyrene microplastics on the extracellular and intracellular dissolved organic matter released by Skeletonema costatum using a novel in situ method.

Microplastics (MPs) affect the physicochemical algal-dissolved organic matter properties, indirectly influencing the environmental behavior of contaminants including persistent organic pollutants and heavy metals. Limited research is available on the roles played by intracellular- and extracellular-dissolved organic matter (I-DOM and E-DOM) in the processes that affect the environmental behavior of contaminants. Furthermore, the effects of MPs on the production of I-DOM and E-DOM, as well as their environmental behaviors, remain uncertain. A critical issue lies in the challenge of quantitatively identifying I-DOM and E-DOM in situ. In this work, a new fluorescence ratio method was developed and applied to in situ examine the impacts of polystyrene (PS) MPs (50, 500 nm, and 5 µm) on the I-DOM and E-DOM released by Skeletonema costatum (S. costatum). The experimental results indicated that the detection limits were 0.06 mg L-1, with the respective minimum detectable proportions being 2% for both E-DOM and I-DOM. The suppressive effects of 10-50 mg L-1 of 50 and 500 nm PS MPs on the cell proliferation of S. costatum and the E-DOM secretion were most pronounced on day 6. And the rates of suppression of E-DOM secretion were 10.1%-18.2% and 4.2%-13.9%, respectively. The exposure of algal cells to 50 mg L-1 of 50 and 500 nm PS MPs led to cell rupture and the leakage of I-DOM on day 6. This suggests that the developed method in the laboratory could offer a promising approach for studying the generation of E-DOM and I-DOM in situ, as well as their environmental behaviors affected by MPs.

Rapid detection of microplastics/nanoplastics directly exposed to blood during intravenous injections via mie scattering spectra.

Microplastics/nanoplastics (M/NPs) are pervasive in the environment, leading to inevitable human exposure through various pathways and raising significant public and scientific concern. Understanding the sources and levels of M/NPs in human blood is crucial for environmental health studies. This work examined the content, type, shape, and size of M/NPs released directly into the bloodstream from medical devices via saline solution during intravenous (IV) injection. The results of the Mie scattering spectra method show that the M/NPs content from infusion bags was 1.0 ± 0.7 µg/L, mainly fibers, polyethylene, and polypropylene, with fragments being predominant. During a IV process, the initial 12 mL of saline from infusion tubes contained 8.4 ± 3.6 µg/L of M/NPs, primarily polyvinyl chloride and fibers. These results suggest that M/NPs exposure during IV therapy mainly originates from infusion tubing, necessitating high concern for exposure risks. Recommendations include: 1) reducing non-essential IV treatments, 2) discarding the initial 12 mL of saline solution flowing through the tubing during essential IV therapy, and 3) expediting the development of legal requirements and detection standards by national authorities and the healthcare industry to mitigate the risk of M/NPs exposure in the bloodstream.

A powerful method for In Situ and rapid detection of trace nanoplastics in water-Mie scattering.

The pervasive presence of nanoplastics (NPs) in environmental media has raised significant concerns regarding their implications for environmental safety and human health. However, owing to their tiny size and low level in the environment, there is still a lack of effective methods for measuring the amount of NPs. Leveraging the principles of Mie scattering, a novel approach for rapid in situ quantitative detection of small NPs in low concentrations in water has been developed. A limit of detection of 4.2 µg/L for in situ quantitative detection of polystyrene microspheres as small as 25 nm was achieved, and satisfactory recoveries and relative standard deviations were obtained. The results of three self-ground NPs showed that the method can quantitatively detect the concentration of NPs in a mixture of different particle sizes. The satisfactory recoveries (82.4% to 110.3%) of the self-ground NPs verified the good anti-interference ability of the method. The total concentrations of the NPs in the five brands of commercial bottled water were 0.07 to 0.39 µg/L, which were directly detected by the method. The proposed method presents a potential approach for conducting in situ and real-time environmental risk assessments of NPs on human and ecosystem health in actual water environments.

Occurrence and distribution of lipophilic marine algal toxins in the coastal seawater of Southeast China and the South China Sea.

The composition, levels, and spatial distribution of dissolved lipophilic marine algal toxins (LMATs) including cyclic imines (CIs), yessotoxins (YTXs), okadaic acid (OA) and its derivatives, pectenotoxins (PTXs), azaspiracids (AZAs), and brevetoxins (BTXs) in the coastal waters of Southeast China (Xiamen) and the South China Sea (Hainan Island and Beibu Gulf) were investigated and compared for the first time. Dissolved AZA3 was firstly detected in the coastal seawater of China. OA and PTX2 were widely distributed in the three areas studied. Gymnodimine (GYM), 13-desmethyl spirolide C (SPX1), YTX, and homo-yessotoxins (h-YTX) were found mainly in the South China Sea. The average ∑LMAT concentrations in the coastal waters of Xiamen, Hainan Island, and Beibu Gulf were 10.02 ng/L, 4.21 ng/L, and 44.27 ng/L, respectively. More groups and much higher concentrations of LMATs occurred in the South China Sea than that in the other sea areas of China.

A novel open-tubular capillary electrochromatography with magnetic nanoparticle coating as stationary phase.

A novel open-tubular capillary electrochromatography (OT-CEC) with modified core/shell magnetic nanoparticles coating as stationary phase was introduced using external magnetic force to fix magnetic nanoparticles. The magnetic nanoparticles coating inside the capillary columns could be easily regenerated by removing and re-applying the external magnetic field. Magnetic field intensity, concentration and flow rate of nanoparticles suspension were investigated to achieve simple and stable preparation. Mixture of five organic acids was used as the marker sample to evaluate the OT-CEC system, and the relative column efficiency of anthranilic acid reaches 220,000 plates/m. The excellent within-column and between-column repeatability has been testified with the RSDs of retention time of less than 1.51 and 5.29%, respectively. The aqueous extract of rhizoma gastrodiae was analyzed by the OT-CEC system, and 23 peaks were eluted in 30 min. Compared with conventional open-tubular capillary column, this new system shows faster separation speed and higher column efficiency from the larger surface area of nanoparticles. It has great potential in the method development for the analysis of complex samples, since magnetic coating can effectively prolong the column life by expediently replacing stationary phase to eliminate the pollution or irreversible adsorption.

Theoretical and experimental investigations on migration behavior of weak monoprotic acids in continuous two-dimensional ion exchange/reversed phase CEC.

A continuous 2D ion exchange/RP CEC system was constructed in this report and retention characteristics of weak monoprotic acids in the column were investigated theoretically. The transport equations were deduced for predicting migration behavior of weak monoportic acids based on mixing model combining ion exchange, RP, and electrophoretic separation mechanism. The influences of separation voltage, length of capillary, pH value, and ionic strength of buffer and concentration of organic modifier in mobile phase on the separation were well described by the equations. It was verified that the migration rate of solute was linearly related to voltage in the case of lower voltage, decreased with the increase of the first-dimensional length, and [H+]. The retention time of solute increased with enhancing ionic strength and concentration of organic modifier. These theoretical results were all demonstrated by the relevant experiments. The relevant application was performed for the aqueous extract of Rhizoma gastrodiae, showing the obvious potential in method development for the analysis of complex samples.

How surfactants affect the depuration of polycyclic aromatic hydrocarbons adsorbed on the mangrove leaf surfaces: insight from an in situ method.

The effects of sodium dodecyl benzene sulfonate (SDBS), polyoxyethylene (20) sorbitan monolaurate (Tween 20), and their mixtures on the depuration of anthracene (Ant) and fluoranthene (Fla) individually adsorbed on the Kandelia obovata (Ko) leaf surfaces were in situ investigated. The Ko original leaf-wax microstructures have been destroyed by SDBS, Tween 20, and their mixtures at or above their critical micelle concentration (CMC). The volatilization rate constants (kV) of the adsorbed PAHs decreased with surfactants at or above their CMC resulting from the plasticizing effect and a decrease in the polarity of the Ko leaf-waxes induced by surfactants. Moreover, the photolysis rate constants (kP) of the adsorbed PAHs decreased with SDBS while increased with Tween 20 and their mixtures at or above their CMC, which can be attributed to effects of surfactants on the light adsorption behavior of Ko leaf-waxes. Overall, the effects of surfactants on the depuration of the adsorbed PAHs were dependent not only on the physical-chemical properties of surfactants but also on the micro-environment of the substrates adsorbed the PAHs. These results are of great significance for further understanding the accumulation of PAHs and could expand our knowledge about the migration mechanism of PAHs from the atmosphere by mangrove leaf surface micro-zones.

High-Efficiency and Wavelength-Tunable Near-Infrared Emission of Lanthanide Ions Doped Lead-Free Halide Double Perovskite Nanocrystals toward Fluorescence Imaging.

Near-infrared (NIR) fluorescent materials show unique photophysical properties, which make them widely used in optical communication, night vision imaging, biomedicine, and other applications. However, the development of high-efficiency and wavelength-tunable NIR nanomaterials is still a challenge. Herein, a series of lanthanide ions doped Cs2AgIn0.99Bi0.01Cl6 double perovskite nanocrystals (DPNCs) with wavelength-tunable NIR light emission (800-1600 nm) have been synthesized. The optimal photoluminescence quantum yield (PLQY) of the DPNCs reaches 66.7%, which is a record value for DPNCs. It is mainly attributed to the contribution of NIR emission of lanthanide ions doped into DPNCs. More importantly, the series of NIR emission wavelengths of lanthanide ions doped Cs2AgIn0.99Bi0.01Cl6 DPNCs include not only shorter-wavelength NIR light (≤900 nm) but also longer-wavelength NIR light (>900 nm), which are more appropriate for foodstuff analysis and medical diagnosis applications. Furthermore, 11.2% Nd3+ doped Cs2AgIn0.99Bi0.01Cl6 DPNCs with the optimal PLQY were embedded in a polymethyl methacrylate (PMMA) polymer matrix (DPNCs@PMMA), and the stability of DPNCs modified by PMMA has been greatly improved. Finally, the 11.2% Nd3+ ions doped Cs2AgIn0.99Bi0.01Cl6 DPNCs@PMMA based NIR LEDs have demonstrated good night vision and human tissue penetration. This work indicates that lanthanide ions doped DPNCs have a potential in NIR light applications and could inspire future research to explore novel lanthanide ions doped semiconductor NCs based NIR LEDs.

Highly efficient and stable red perovskite quantum dots through encapsulation and sensitization of porous CaF2:Ce,Tb nanoarchitectures.

Lead halide perovskite quantum dots (PQDs) are extremely unstable when exposed to oxygen, water and heat, especially red CsPbBrxI3-x (x = 0, 0.5, 1.2) PQDs. This seriously hinders their practical application. Here, red CsPbBrxI3-x (x = 0, 0.5, 1.2) PQDs have been successfully encapsulated in porous CaF2:Ce,Tb hierarchical nanospheres (HNSs), which not only greatly improved the stability of PQDs, benefitting from the protection of the CaF2 shell, but also maintained the high photoluminescence quantum yield (PLQY) of PQDs, benefitting from the sensitization of Tb3+ ions. More importantly, porous CaF2:Ce,Tb nanoarchitectures can prevent aggregation quenching and anion exchange of PQDs. Therefore, the CaF2:Ce,Tb&CsPbBrxI3-x (x = 0, 0.5, 1.2) composite powder can have high PLQY comparable to that of the PQD powder. In view of this, CaF2:Ce,Tb&CsPbBr1.2I1.8 composite based red light-emitting diodes (LEDs) are prepared, and they are very suitable as a supplementary light source for plant lighting. Furthermore, white LEDs are also prepared by coating the CaF2:Ce,Tb&CsPbBr3 and CaF2:Ce,Tb&CsPbBr1.2I1.8 composite on a 450 nm chip. The optimum luminous efficiency is 61.2 lm W-1, and the color rendering index is 91, which are comparable to the current highest values. This shows that the composite composed of PQDs has great potential in LED lighting.

The distribution and retained amount of benzo[a]pyrene at the micro-zones of mangrove leaf cuticles: Results from a novel analytical method.

Plant leaf cuticles play a critical role in the accumulation and transport of atmospheric polycyclic aromatic hydrocarbons (PAHs). The relationship between the distribution and retained amount of PAHs on the leaf cuticles and the leaves micro-zone structures is still unclear. In this study, a confocal microscopic fluorescence spectral analysis (CMFSA) system with a spatial resolution of 200 nm was established as a direct and noninvasive means to determine the microscopic distribution and quantify the retained amount of benzo[a]pyrene (B[a]P) at Aegiceras corniculatum (Ac), Kandelia obovata (Ko) and Avicennia marina (Am) leaf cuticle micro-zones (0.096 mm2). The linear ranges for the established method were 10-1900 ng spot-1 for Ac, 15-1700 ng spot-1 for Ko and 30-1800 ng spot-1 for Am, and the detection limits were 0.06 ng spot-1 for Ac, 0.06 ng spot-1 for Ko and 0.07 ng spot-1 for Am. Notably, B[a]P formed clusters and unevenly distributed at the leaf cuticles. On the adaxial cuticles, B[a]P was mainly accumulated unevenly along the epidermis cell wall, and it was also distinctively distributed in the secretory cells around salt glands for Ac and Am. On the abaxial leaf cuticles, B[a]P was concentrated in the salt glands and stomata apart from being unevenly distributed in the epidermis cell wall. Moreover, the amount of B[a]P retained presented a negative correlation with the polarity of leaf cuticles, which resulted in the amount of B[a]P retained on the adaxial leaf cuticles being significantly higher than that on abaxial leaf cuticles. Our results provide a potential in situ method for investigating the distribution and retained amount of PAHs at plant leaf surface micro-zones, which would contribute to further studying and understanding the mechanism of migration and transformation of PAHs by plant leaves from a microscopic perspective.

Potential ability of different types of cyclodextrins to modulate the interaction between bovine serum albumin and 1-hydroxypyrene.

Hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) can bind with functional biomacromolecules and thus cause toxic effects in vivo. Four types of cyclodextrins (CDs) were selected to explore their potential ability to regulate the bindings between 1-hydroxypyrene (1-OHPyr) and bovine serum albumin (BSA) using multi-spectroscopic methods combined with molecular docking. The results showed that the four CDs caused varied modulating effects on the binding of BSA with 1-OHPyr, and the effects of γ-CD and (2-hydroxypropyl)-ß-CD (HPCD) are the most significant. Specifically, γ-CD and HPCD could significantly reduce the binding affinity between 1-OHPyr and BSA, inhibit the micro-environmental changes of tryptophan residues, and slightly recover the helicity of BSA. The interactions and inclusion behavior of CDs with 1-OHPyr was the main reason why CDs could affect the binding of 1-OHPyr to BSA. The results indicated that γ-CD and HPCD might have potential application value in regulating the toxic effects of OH-PAHs.